i had a clown use 2 concrete blocks onder his front tires,so he could pull the trans,blocks broke...he will never pull another trans...it killed him........

I know of people who will argue a concrete block is safe if it is turned the right way but while it may be a bit less likely to crumble there is no safe way to use a concrete block. Even with the block resting on a smooth solid surface and a board on top to distribute the weight it's not safe, while that arrangement should theoretically hold several times the weight of the car it would depend entirely on the block's integrity and there is simply no way of knowing if the block is solid or ready to fall apart!